A color filter is an important component which directly affects the color display quality of a liquid crystal display. The color filter is configured such that small resin films each containing a pixel of any of three primary colors of RGB (red, green, and blue) are arranged on a transparent glass substrate, and is required to have abilities important to a color display such as high light transmittance, high contrast, and chromaticity. At present, since a wide variety of properties such as properties required for panel structure such as light resistance and smoothness, and properties required for panel assembly such as heat resistance, chemical resistance, and dimensional stability are demanded, a pigment is used as a colorant for producing a color filter. In order to achieve high performance, it is necessary to disperse a pigment in a state close to primary particles, and a dispersant having excellent dispersion performance is used for this purpose.
However, since heating is performed in producing a color filter, there are problems that the color tone is changed after heating and the color purity is decreased. Therefore, in order to avoid these problems, various studies have been carried out.
Patent document 1 discloses a method utilizing an amine oxide group-containing maleic anhydride copolymer as a dispersant to be used for expensive industrial painting such as automobile painting. The productivity thereof and the color tone of the dispersant itself have been improved, however, there is no description of heat resistance.
Further, Patent documents 2 and 3 propose a polyallylamine derivative in which a polyester or the like is introduced into an amino group of a polyamine as a dispersant to be used for a pigmented paint, a printing ink, coloring a plastic, etc., however, there is no description of heat resistance.
Patent document 4 describes that the heat resistance is improved by adding an antioxidant such as a phosphite triester to a pigment dispersant ink, however, sufficient heat resistance has not been achieved yet.